This invention relates generally to an apparatus and method for controlling a work implement of a work machine and, more particularly, to an apparatus and method for providing coordinated control of the work implement to produce linear movement of the work implement.
Work machines, such excavators, backhoe loaders, wheel loaders, telescopic material handlers, and the like, are adapted for digging, loading, pallet-lifting, etc. These operations usually require the use of two or more manually-operated control levers for controlling the position and orientation of the work implement.
As an example, a telescopic material handler includes a telescoping boom having a load-engaging member, e.g., pallet lifting forks, connected at one end of the boom. Two control levers are used to independently actuate hydraulic cylinders adapted for controlling the angle of the boom with respect to a reference plane, and the length of the boom, respectively.
Frequently, linear or straight-line movement of the forks are required, e.g., when the forks of the telescopic material handler are to be driven under a pallet in order to lift the pallet. In order to effect such linear movement, the angle of the boom and the length of the boom must be simultaneously controlled. Extensive operator skill is required for coordinating control of the levers while performing these complex operations, thus increasing operator fatigue for skilled operators, and the training time required for lesser skilled operators.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention, an apparatus for providing coordinated control of an implement of a work machine having a frame, the implement includes a boom having a first end portion and a second end portion, with the first end portion pivotally connected to the frame and the second end portion connected to a load-engaging member. The apparatus includes a position sensor adapted for providing a position signal, and an input device adapted for delivering a desired velocity signal indicative of the desired velocity of the load-engaging member. The desired velocity includes a desired angular velocity and a desired linear velocity. The apparatus receives the position signal and the desired velocity signal, and determines an actual path of travel of the load-engaging member, and a desired path of travel of the load-engaging member. The apparatus further modifies the desired angular velocity and the desired linear velocity in response to a deviation between the actual and desired paths of travel.
In another aspect of the present invention, a method for providing coordinated control of an implement of a work machine having a frame is disclosed. The implement includes a boom having a first end portion and a second end portion, with the first end portion pivotally connected to the frame and the second end portion connected to a load-engaging member. The method includes the step of sensing a position of the load-engaging member, and responsively delivering a position signal. The method also includes the steps of delivering a desired velocity signal indicative of a desired velocity of the load-engaging member, the desired velocity including a desired angular velocity and a desired linear velocity. The method further includes the steps of determining an actual path of travel of the load-engaging member as a function of the position signal, determining a desired path of travel of the load-engaging member as a function of the desired velocity signal, and modifying the desired angular velocity and the desired linear velocity in response to a deviation between the actual and desired paths of travel.